Method and system for vision enhancement

ABSTRACT

Methods and systems for modifying or enhancing vision are described. In exemplary embodiments, neural or neuromuscular activity is analyzed to determine a focus or other quality that is desired of a visual image, and the focus or quality information used as a basis for controlling an adjustable lens system or optical system.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to, claims the earliest availableeffective filing date(s) from (e.g., claims earliest available prioritydates for other than provisional patent applications; claims benefitsunder 35 USC § 119(e) for provisional patent applications), andincorporates by reference in its entirety all subject matter of thefollowing listed application(s); the present application also claims theearliest available effective filing date(s) from, and also incorporatesby reference in its entirety all subject matter of any and all sibling,parent, grandparent, great-grandparent, etc. applications of thefollowing listed application(s):

-   1. U.S. patent application entitled TEMPORAL VISION MODIFICATION,    naming W. Daniel Hillis, Roderick A. Hyde, Muriel Y. Ishikawa,    Edward K. Y. Jung, Nathan P. Myhrvold, Clarence T. Tegreene and    Lowell L. Wood, Jr. as inventors, filed substantially    contemporaneously herewith.-   2. U.S. patent application entitled VISION MODIFICATION WITH    REFLECTED IMAGE, naming W. Daniel Hillis, Roderick A. Hyde,    Muriel Y. Ishikawa, Edward K. Y. Jung, Nathan P. Myhrvold,    Clarence T. Tegreene and Lowell L. Wood, Jr. as inventors, filed    substantially contemporaneously herewith.-   3. U.S. patent application entitled METHOD AND SYSTEM FOR ADAPTIVE    VISION MODIFICATION, naming Eleanor V. Goodall, W. Daniel Hillis,    Roderick A. Hyde, Muriel Y. Ishikawa, Edward K. Y. Jung, Nathan P.    Myhrvold and Lowell L. Wood, Jr. as inventors, filed substantially    contemporaneously herewith.-   4. U.S. patent application entitled ADJUSTABLE LENS SYSTEM WITH    NEURAL-BASED CONTROL, naming Eleanor V. Goodall, W. Daniel Hillis,    Muriel Y. Ishikawa, Roderick A. Hyde, Edward K. Y. Jung, Nathan P.    Myhrvold and Lowell L. Wood, Jr. as inventors, filed substantially    contemporaneously herewith.

TECHNICAL FIELD

The present application relates, in general, to the field of opticalsystems for improving and enhancing vision.

BACKGROUND

The use of lenses for correcting vision problems produced bydeficiencies in the optical system of the human eye has been known formany years. FIG. 1A illustrates, in schematic form, the anatomy of thehuman eye 10. Light enters eye 10 through cornea 12, passes through lens14, and strikes retina 16, the light-detecting inner surface of the eye.The fovea 18 is a central region of retina 16 having particularly highacuity. Lens 14 is attached around its periphery to zonular fibers 20.Zonular fibers 20 are connected to ciliary body 22. Ciliary body 22 is asphincter muscle which opens when it is relaxed, thereby generatingtension in zonular fibers 20. Ciliary body 22 releases tension onzonular fibers 20 when it is contracted. Lens 14, because of itsinherent elastic properties, tends to assume a rounded form when it isnot subject to external forces. Thus, when ciliary body 22 contracts,lens 14 becomes more rounded, while relaxation of ciliary body 22produces flattening of lens 14. Cornea 12 provides a significant portionof the refractive power of the optical train of the eye, but thecapacity for accommodation is contributed by lens 14.

FIG. 1B illustrates a relaxed (unaccommodated) eye 10, in which lens 14is flattened. As indicated by the solid lines in FIG. 1B, light fromdistant objects will be focused on retina 16 (and specifically, on fovea18) by lens 14, but light from near objects (indicated by the dashedlines) will be focused behind the retina, and thus appear out of focusat the retina. FIG. 1C illustrates an accommodated eye 10, in which lens14 has assumed a more rounded form. In the accommodated eye, light fromnear objects (indicated by dashed lines) is focused on retina 16 (fovea18), while light from distant objects (indicated by solid lines) isfocused in front of the retina, and thus is out of focus at retina 16.

In a normal, healthy eye, adjustment of lens 14 is sufficient to focusimages on retina 16 within a wide range of distances between the visualtarget-object and the eye. Myopia (near-sightedness) and hypermetropia(far-sightedness) occur when images entering the eye are brought intofocus in front or in back of the retina, respectively, rather thanexactly on the retina. This is typically caused by the eyeball being toolong or too short relative to the focal-adjustment range of the lens.Eyeglasses with spherical focusing lenses of the appropriate opticalrefractive power can be used to compensate for myopia or hypermetropia.

Another common and readily corrected visual problem is astigmatism, afocusing defect having orientation-dependence about the optical axis ofthe eye that may be corrected by interposition of a cylindrical lenshaving appropriate refractive power and axis-angle of orientation. Othervisual focus problems exist as well (e.g., coma and other higher orderoptical aberrations), but are less readily characterized and moredifficult to correct in a practical manner. In general, focal problemscaused by irregularities in the dimensions of the cornea, lens, oreyeball can be corrected, providing the optical properties of the eyecan be characterized and a suitable (set of) optical element(s)manufactured and then positioned relative to the eye.

Aging subjects may experience presbyopia, a decrease in the ability tofocus on proximate visual targets caused by reduced flexibility of theeye lens relative to the tractive capabilities of the operativemusculature attached thereto. Difficulty in focusing on such proximatevisual targets can be alleviated with the use of ‘reading glasses’.Subjects who require correction for myopia as well as presbyopia may use“bifocal” glasses having lens regions that provide correction for both‘near’ and ‘far’ vision. The subject selects the type of correction bylooking toward the visual target through the appropriate portion of thelens. Elaborations and extensions on such systems are now common,including “trifocal glasses” and “progressive glasses,” the latterfeaturing a continuous gradation in optical properties across a portionof the eyeglass and thus of the visual field thereby regarded.

Adjustable optical systems are used in a wide variety of devices orinstruments, including devices that enhance human vision beyond thephysiological range, such as telescopes, binoculars, and microscopes, aswell as a numerous devices for scientific and industrial applicationsindependent of human vision, such as in test, measurement, control, anddata transmission. Such devices typically make use of complex systems ofmultiple lenses and optical components that are moved with respect toeach other to provide a desired level of focus and magnification.Adjustable lens systems that have been proposed for use in eyeglass-typevision enhancement include electroactive lenses, as described in U.S.Pat. Nos. 6,491,394 and 6,733,130 and various types of fluid lenses, asdescribed in U.S. Pat. Nos. 4,466,706 and 6,542,309, as well as assortedmulti lens systems (see e.g., U.S. Pat. Nos. 4,403,840 and 4,429,959).

Various methods have been developed for measuring neural activity.Electrical measures of neural activity can be obtained from electrodespositioned within a neural structure to record activity from one or afew cells, or from electrodes placed on a skin surface to measureelectrical fields, typically representing the activity of multiplecells. Magnetic fields generated by the nervous system can also bemeasured by devices such as SQUIDs (superconducting quantum interferencedevices), which may be placed on the scalp to measure magnetic fieldsfrom the brain. Other methods, such as magnetic resonance imaging andoptical (spectroscopic) measurements permit neural activity to bedetermined indirectly by measuring correlates of brain activity such asblood flow or metabolic activity. Similarly, muscle activity can beassessed through measurement of electrical and magnetic fields generatedby muscles (e.g., electromyographic measures or EMG), as well as bymeasurements of muscle force, displacement, or related parameters.

SUMMARY

A method and system for providing adaptive vision modification uses oneor more adjustable lenses. Automatic, real-time lens adjustment may beused to correct the subject's near and far vision during routineactivities or to provide vision enhancement beyond the physiologicalranges of focal length or magnification, in support of specializedactivities. Automatic lens adjustment may be based upon detection ofneural or muscular activity correlated with the orientation or the stateof focus of the eye. Various features of the present invention will beapparent from the following detailed description and associateddrawings.

BRIEF DESCRIPTION OF THE FIGURES

The features of the present invention are set forth in the appendedclaims. The invention may best be understood by making reference to thefollowing description taken in conjunction with the accompanyingdrawings. In the figures, like referenced numerals identify likeelements.

FIG. 1A illustrates the anatomy of the eye;

FIG. 1B illustrates focusing of the normal eye for distance vision;

FIG. 1C illustrate focusing of the normal eye for near vision;

FIG. 2 illustrates an embodiment in which components are mounted in aneyeglass frame;

FIG. 3 is a schematic diagram of an embodiment of the invention asdepicted in FIG. 2;

FIG. 4 is a flow diagram of the operation of the embodiment of FIG. 3;

FIG. 5 illustrates an alternative embodiment;

FIG. 6 is a flow diagram of the operation of the embodiment of FIG. 5;

FIG. 7 depicts an alternative method of positioning sensors;

FIG. 8 is an embodiment including a contact lens system;

FIG. 9 is an embodiment including an intraocular lens;

FIG. 10 is a flow diagram illustrating lens system adjustment;

FIG. 11 illustrates an embodiment having two parallel optical paths;

FIG. 12 illustrates the construction of an adjustable lens system havingtwo parallel optical subsystems;

FIG. 13 shows a helmet-mounted embodiment; and

FIG. 14 shows implementation in an alternative mounting.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. The detaileddescription and the drawings illustrate specific exemplary embodimentsby which the invention may be practiced. These embodiments are describedin sufficient detail to enable those skilled in the art to practice theinvention. It is understood that other embodiments may be utilized, andother changes may be made, without departing from the spirit or scope ofthe present invention. The following detailed description is thereforenot to be taken in a limiting sense, and the scope of the presentinvention is defined by the appended claims.

Throughout the specification and claims, the following terms take themeanings explicitly associated herein unless the context dictatesotherwise. The meaning of “a”, “an”, and “the” include pluralreferences. The meaning of “in” includes “in” and “on.” A reference tothe singular includes a reference to the plural unless otherwise statedor inconsistent with the disclosure herein. In particular, thoughreference is frequently made to “the eye” or “the lens”, in mostembodiments two lenses or lens systems will be used, one for each eye ofthe subject, and that, while the operation of the lenses will typicallybe the same, they will typically be adjusted separately to meet theindividual needs of the two eyes.

FIG. 2 illustrates an exemplary embodiment of a system for modifying thevision of a subject 28. Adjustable lens system 26 is positioned withrespect to eye 10 of subject 28 with mounting 30, which in this exampleis an eyeglass frame. Sensors 32 detect neural activity from subject 28which contains components correlating with the quality or focalcondition of the visual input. Sensors 32 may be positioned with respectto the head of subject 28 by means of a wearable positioning means,which in this example is a headband 37 connected to bow 35 of eyeglassframe 30. Data from sensors 32 is routed to processor 34. Processor 34processes the data and based upon the processed data generates a controlsignal that drives adjustable lens system 26 to provide a modifiedvisual input to subject 28. Power supply 36, also mounted in bow 35 ofmounting 30, provides power to adjustable lens system 26, sensor 32, andprocessor 34. Connections between various system components may be viaconventional electrical cabling or wiring, or may be remote or wirelessconnections formed by RF or inductive couplings.

FIG. 3 is a schematic diagram of an exemplary embodiment, illustratingthe functional relationships of various system components. A visualinput 40 passes through adjustable lens system 26 and eye optics 50, andstrikes retina 16, where it is detected (as modified visual input 42) byphotoreceptors in the retina 16 of the eye. A neural signal is generatedthat travels through the optic pathways of brain 70. The optic pathwaysmay include, but are not limited to, the retina, optic nerve, lateralgeniculate nucleus, superior colliculus, and visual cortex. Neuralactivity may be detected from various regions of the brain, particularlyfrom optic pathways of the brain but also from other cortical areas.Neural activity is detected by one or more sensors 32 and routed toprocessor 34 as neural signal 52. Processor 34 includes signal analyzer56 and lens system controller 58. Processor 34 may include variouscombinations of analog or digital electronic circuitry, discretecomponents or integrated circuits, and/or hardware, software, orfirmware under computer or microprocessor control, including opticalanalog devices. Processor 34 may include a variety of functional and/orstructural components for supporting the function of signal analyzer 56and lens system controller 58, such as memory, timing, and datatransmission structures and devices. Neural signal 52 is processed bysignal analyzer 56 to obtain information relating to the focal conditionof the image on retina 16. A focal condition signal 60 reflecting thequality of the retinal image as determined from neural signal 52 isgenerated by signal analyzer 56 and sent to lens system controller 58.Lens system controller 58 generates lens system control signal 62, whichis sent to adjustable lens system 26. Lens system controller 58 may alsoreceive as input a lens state signal 68 from adjustable lens system 26,which provides information regarding the state of adjustable lens system26. Lens state information may be used in computations performed by oneor both of signal analyzer 56 and lens system controller 58. Adjustablelens system 26, sensor 32, and processor 34 and its components, signalanalyzer 56 and lens system controller 58, may all be powered by powersupply 36. Alternatively, certain components may have separate powersources. The invention is not limited to any particular power supplyconfiguration.

FIG. 4 is a process flow diagram for a method of enhancing the vision ofa subject, as may be carried with a system as depicted in FIG. 3. Instep 82, a neural signal is detected from a subject. Subsequently, instep 84, an indicator of focal condition is detected from the neuralsignal. The indicator of focal condition correlates with state of focusof a real-time visual input to the subject. In step 86, a lens system isadjusted responsive to the indicator of focal condition. In order toprovide ongoing visual enhancement to the subject, after step 86,process control returns to step 82, and the process is repeated as longa visual enhancement is desired.

FIG. 5 is a schematic diagram of a further embodiment suited for certainspecialized applications requiring image magnification outside thephysiological range of human vision. As illustrated in FIG. 3, visualinput 40 passes through adjustable lens system 26 and eye optics 50, andstrikes retina 16 as modified visual input 42, where it is detected byphotoreceptors in the retina of the eye. Neural activity is detected byone or more sensors 32 and routed to processor 34 as neural signal 52.Neural activity may be detected from various regions of brain 70.Processor 34 includes signal analyzer 56, which processes 52 to generatefocal condition signal 60, and lens system controller 58, whichgenerates lens system control signal 62 responsive to focal conditionsignal 60. Neural signal 52 is processed by signal analyzer 56 to obtaininformation relating to the focal condition of the retinal image. Afocal condition signal 60 reflecting the quality of the retinal image isgenerated by signal analyzer 56 and sent to lens system controller 58.

Processor 34 is generally as described above in connection with FIG. 3.However, processor 34 is adapted to also receive a magnification factorinput 140, and generation of lens system control signal 62 is based uponmagnification factor input 140 as well as focal condition signal 60.Magnification factor input 140 may be entered into processor 34 byvarious methods; it may be preprogrammed at a fixed value or entered bythe subject. It is contemplated that the magnification factor will beused for special applications (e.g., close-up detail work or viewingdistant objects) and that the subject may prefer to adjust themagnification to meet the requirements of a particular application.Manual selection of the magnification factor may be accomplished, forexample, by configuring the device with one or more preprogrammedmagnification factor values, and having the subject press a button onthe eyeglass frame to cycle through magnification values until arrivingat the desired magnification value; clearly provision also may be madefor continuously-variable magnification control. Alternatively, adesired degree of magnification may be derived by the control processor34 based upon some portion of the neural input 52. As describedpreviously, lens system control signal 62 is sent to adjustable lenssystem 26. Lens system controller 58 may also receive as input a lensstate signal 68 from adjustable lens system 26, which providesinformation regarding the state of adjustable lens system 26. Lens stateinformation may be used in computations performed by one or both ofsignal analyzer 56 and lens system controller 58. Adjustable lens system26, sensor 32, and processor 34 and its components, signal analyzer 56and lens system controller 58, may all be powered by power supply 36, oralternatively, certain components may have separate power sources.

The method of operation of the embodiment of the system shown in FIG. 5is depicted in the flow diagram of FIG. 6. At step 148, a desiredmagnification factor input is accepted, which may be accomplished byvarious means, as described above. At step 150, a neural signal isdetected from the subject. At step 152, an indicator of focal conditionis determined from the neural signal, and at step 154, the lens systemis adjusted based upon the indicator of focal condition and themagnification factor. In order to provide ongoing vision modification,at step 156 process control is returned to step 150, and steps 150through 154 are repeated for as long as vision enhancement at theselected magnification is desired. Note that the process depicted inFIG. 6 may be part of a larger process, and that by including additionalcontrol loops, it would be a simple matter to provide for the input ofan updated desired magnification factor value, during an ongoing controlprocess.

As illustrated by the foregoing examples, the various embodiments maycomprise a number of basic components, the structure and operation ofwhich will now be described in greater detail. These components mayinclude an adjustable lens system 26, which, as represented in FIG. 3,one or more sensors for detecting a neural or neuromuscular signal(e.g., sensor 32, as shown in FIGS. 3 and 5); processor 34, whichincludes a signal analyzer 56 and lens system controller 58; and powersupply 36.

Various types of adjustable lens systems may be used in practice, andthe invention is not limited to any particular type of adjustable lenssystem or set thereof, these two terms being used synonymously herein.However, certain adjustable lens systems may be more suitable thanothers, with small size, low weight, rapid adjustment, and compatibilitywith other system components being considerations for some applications.Depending on the particular intended application, certain considerationsmay be of greater importance than others, and thus the best choice oflens system will vary from application to application. While in somecases a single lens may be preferable due to smaller size and lighterweight, the term “adjustable lens”, as used herein, refers to adjustablelenses and lens systems, including combinations of one or more lenses aswell as other optical elements, which may include reflectors, refractiveelements, beam splitters, active or passive filters, and so forth.

Conventional eyeglass lenses and contact lenses are typicallycharacterized by their spherical lens strength or optical power(expressed in positive or negative diopters, the reciprocal of theirfocal length measured in meters-distance), cylindrical lens strength,and cylindrical axis orientation. Lenses may modulate the spatialfrequency content of an image formed thereby (e.g., by adjusting thefocus of the image) and may also modulate the light intensity of theimage as a function of wavelength, e.g., by spectrally-dispersiveproperties of their bulk composition or coatings applied to theirsurfaces. Suitable adjustable lenses or lens systems may becharacterized by these and additional focus or image-quality parameters.Lens systems may be used to provide image magnification outside thephysiological range of human vision, and hence may be characterized by amagnification strength factor as well. An adjustable lens system used toprovide vision correction may preferably permit the adjustment of eachof these parameters, although in particular applications and forparticular subjects, not all of these parameters may need to beadjusted. Independent adjustment of each of the various parameters maybe desirable in some cases, but in many cases may not be required.

A number of designs for fluid-based adjustable lenses have been proposedwhich may be suitable for use. Fluid lenses utilize one or more fluidshaving appropriately selected indices of refraction. One approach is toenclose fluid within a deformable shell, and to increase fluid volume orpressure to deform the shell and thus change the optical strength of thelens, as disclosed in U.S. Pat. Nos. 4,466,706, 5,182,585, 5,684,637,6,069,742, 6,542,309 and 6,715,876, which are incorporated herein byreference. Another approach is to utilize two immiscible liquids ofdiffering refractive properties contained within a chamber, and modifythe shape of the fluid-fluid interface in order to change the opticalstrength of the lens. The surface tension properties of the interior ofa chamber are modified, for example, through an applied voltage (andthus electric field and gradients thereof) to adjust the shape of thefluid-fluid interface. Such fluid lenses, as disclosed in U.S. Pat. No.6,369,954, which is incorporated herein by reference in its entirety,may also be suitable for use in some applications.

Another suitable type of adjustable lens or lens system may be anelectro-active lens as described in U.S. Pat. Nos. 4,300,818, 6,491,394and 6,733,130, also incorporated herein by reference. These lensesinclude one or more layers of liquid crystal or polymer gel havingrefractive power that may be modulated, e.g., electrically. An advantageof this type of lens is the refractive power can be adjusted selectivelyin different regions of the lens, making it possible to produce nearlyany desired lens, including a lens that compensates for higher orderoptical aberrations, or a lens having regions with different focalstrengths (comparable to a bi-focal or tri-focal lens), such that all ora portion of the lens can be adjusted. It is also possible to constructa lens system that can be rapidly switched from one focal length toanother with the use of this technology.

In some embodiments, an adjustable lens system may be made up ofmultiple lenses or other optical elements, and adjustment may beaccomplished by moving one optical element with respect to another orwith respect to the subject. Such movements may include one or all ofchanging the distance, angle-of-orientation, or off-axis displacementbetween two or more optical elements. The adjustable lens system mayinclude a lens mechanism and a lens actuator that is used for actuatingthe lens mechanism. Thus, the lens mechanism itself may not receivecontrol signals directly from the lens system controller. A lensmechanism and lens actuator may be formed integrally, or they may beseparate elements depending on the design of the lens system.

Adjustable lens systems may modify incident light in some specifiedmanner. Adjustable lenses may bend (refract) incident light rays; theymay also filter the incident light to modify the spectral composition ofthe incident light or to change the imaged intensity at one or moreselected spectral wavelengths or wavebands. An adjustable lens systemmay have an adjustable transmissivity (or transmittivity), whichadjustment may be wavelength-dependent. In a broad sense, an opticalelement may be any device or system that receives an input image andproduces an output image that is a modified version of the input image;thus in certain embodiments the modified image is not formed entirely oreven in significant part of incident light that has been transmittedthrough the lens system, but partly or mostly (including entirely) oflight that has been generated by the lens structure to form a new image.In some embodiments, the term ‘optical element’ or ‘optical system’ mayencompass systems including cameras and displays. Such an opticalelement may modulate the incident image in ways not possible with lensesthat transmit incident light; e.g., the optical element may transformthe incident image by shifting the spectral content or the intensity ofsome or all wavelengths relative to the incident light corresponding tothe image. Adjusting the optical element may include adjusting one ormore focal lengths, adjusting one or more cylindrical corrections,adjusting one or more distances of an optical element relative to an eyeof the subject, adjusting the orientation-angle of the optical elementwith respect to the optical axis of the eye, adjusting the off-axisdisplacement of one or more optical elements relative to the opticalaxis of the eye, or adjusting the pan-or-tilt of one or more opticalelements relative to the optical axis of the eye.

In one embodiment, the method may be considered to be a method ofmodifying a view of the environment. The method includes steps ofdetecting a neural signal from a subject, extracting informationrelating to an image condition of at least a portion of the view of thevisual environment from the neural signal, determining a modification tothe view based upon information relating to the image condition, andadjusting an optical system to produce modification of the view. Theoptical system may include, but is not limited to, optical componentssuch as lenses, reflectors, refractive elements, active and passiveoptical filtering systems including optical attenuators and amplifiers,and beam splitters such as may be used for modifying incident light. Insome embodiments, rather than modifying transmitted light, the opticalsystem may detect and process an incident image and generate a modifiedversion of all or part of the incident image.

As depicted in FIGS. 3 and 5, an indicator of focal condition may bedetermined from a neural signal detected from the subject. Neuralactivity can be recorded from the brain or other regions of the nervoussystem using a variety of measurement techniques well known to those ofskill in the art, including electrical, magnetic, and opticalmeasurements techniques. Electrical recordings can be made usingelectrodes implanted within the brain or surface electrodes placed onthe scalp or on the surface of the brain. Electrodes may be placed onthe skin, e.g., near the eye, to detect electrical potentials from theretina, as described in U.S. Pat. No. 4,255,023, incorporated herein byreference in its entirety. Implanted electrodes are capable of recordingactivity from one or a small number of nerve fibers or cell bodies. See,for example, the methods and devices described in U.S. Pat. No.6,647,296, incorporated herein by reference in its entirety. Electrodeson the scalp or brain surface record from a large number of neurons inaggregation, providing information about the aggregate activity of largepopulations of neurons, as described in exemplary U.S. Pat. Nos.5,052,401, 6,647,296, and 6,690,959, which are incorporated herein byreference in their entirety.

Magnetic recording techniques can be used as an alternative toelectrical recording techniques (see, e.g. U.S. Pat. No. 6,066,084, andHeeger, D. J. and Ress, P., Nature Reviews Neuroscience, vol. 3, pp.142-151, February 2002, both of which are incorporated herein byreference in their entirety). Superconducting quantum interferencedevices or SQUIDs are among the types of magnetic field-sensing systemsthat can be used to record neural activity, as described in U.S. Pat.Nos. 5,309,095 and 6,195,576, incorporated herein by reference in theirentirety. Other techniques for measuring neural activity include opticaltechniques such as optical coherence tomography and near IR imaging.Measurements of absorption and scattering of visible or IR light mayprovide an indication of neural activity, as described in U.S. Pat. Nos.5,187,672, 5,792,051, 5,853,370, 5,995,857, and 6,397,099, all of whichare incorporated herein by reference in their entirety. Neural signalsmay be recorded by various methods as described herein, by other methodsas are known in the art or may be developed in the future, and are notlimited to any particular neural or neuromuscular recording methods.

In some embodiments, a sensor may be adapted for detecting aneuromuscular signal from the subject. The term neuromuscular signal, asused herein, refers to a signal detected from either a nerve or a musclethat relates to the activation of, or intention to activate, a muscle.Thus, in some cases, the neuromuscular signal may be detected from thenervous system of the subject, including central nervous structures(including, but not limited to motor cortex) as well as peripheralnerves innervating muscles. In other cases, the neuromuscular signal isdetected directly from a muscle. In the case that the neuromuscularsignal is detected from the central or peripheral nervous system, neuralrecording techniques as have been described previously may be used. Notethat the measurement of electrical and magnetic signals from peripheralnerves is well established and a variety of techniques for measuringsuch activity are known to those of skill in the art. Optical techniquesas discussed previously may also be adapted for making peripheralmeasurements. Methods for measuring electrical or magnetic signals frommuscles are well known, and include sensors implanted within a muscle,positioned on the exterior of a muscle, or positioned near, on or undera skin surface near the muscle(s) of interest. The neuromuscular signalmay be an electromyelographic or EMG signal. Such signals may berecorded for example, from an extraocular muscle, a ciliary muscle, theiris, or a facial muscle of the subject. As used herein, “neuromuscularsignal” may also refer to a measure of muscle force, displacement,pressure, volume or related parameters detected with suitabletransducers located in, on, or adjacent a muscle (including, but notlimited to, positions near, on or under the skin surface) in order tomeasure muscle mechanical activity or its correlates.

Neural signals may be detected by various methods, and the signalprocessing and analysis will depend on the type of neural signal and themethod of detection. The term “neural signal”, as used herein, refersnot only to signals that are direct measures of neural activity, butalso to signals that are correlated with neural activity. These mayinclude, but are not limited to, measurements of electrical or magneticfields generated by nerve cells, axons, processes, or fibers;measurements of metabolic activity in nerve cells or supporting cellssuch as glial cells; or measurements of blood flow in selected brainregions, as determined by optical, biochemical, thermal, or othermeasurements. Neural activity may be the activity of individual cells,small numbers of cells or populations of cells, including activitymeasured from cell bodies or cellular processes such as axons, dendritictrees, or nerve fibers, in one or more regions of the central orperipheral nervous system.

Muscular activity refers to activity detected from muscles, includingbut not limited to electric, magnetic or electromagnetic fieldscorresponding to muscle activation, motion, position, relaxation orcontraction. As with neural activity, muscular activity may also bemeasured indirectly through measurement of blood flow, temperature, ormetabolic activity; force or displacement may also be measured, as mayvarious other parameters as known or may be discovered by those ofordinary skill in the art.

The terms signal and signals may be used interchangeably herein, and mayrefer to activity originating from one or more sources detected with theuse of one or more sensors, unless the context dictates otherwise.

Neural and neuromuscular signals suitable for providing feedbackinformation in the various embodiments described herein, and otherembodiments, may be recorded from a variety of neural structures,including but not limited to the cerebral cortex, especially theoccipital region thereof, the retina, optic nerve, lateral geniculatenucleus, superior colliculus, and other portions of the optic pathway,motor nerves innervating muscles of the eyes (especially the ciliarymuscles, extraocular muscles, and iris) and surrounding regions (e.g.,certain facial muscles).

If implanted electrodes or other sensors are used, the sensor(s) may beimplanted within the selected location according to methods described inthe references incorporated above. Detected signals may be transmittedfrom one or more sensors to other system components by RF or inductivecoupling, including but not limited to transponder-type sensing andsignal-transceiving.

In some embodiments, sensors may be positioned on the head of thesubject. In such embodiments it may be desirable to make use of awearable positioning device to position or orient the sensor(s) withrespect to the head of the subject. FIG. 2, for example, illustrates anembodiment in which several sensors 32 are positioned with respect tothe head of subject 28 through the use of a headband 37, which isaffixed to bows 35 of an eyeglass frame. As depicted in FIG. 2, headband37 contains a single row of sensors 32. The width of headband 37 may beadjusted to hold larger numbers of sensors, arranged in an array ofmultiple rows, or in any configuration deemed useful or convenient.Because headband 37 generally overlays regions of the cerebral cortexdevoted to visual processing, sensors positioned by means of headband 27may be well suited for detecting activity from visual processing areasof the cortex. Sensors may also be mounted in or on bow 35, or otherportions of the eyeglass frame.

FIG. 7 illustrates a further embodiment of a wearable positioning devicein which one or more sensors 32 are mounted in specialized bow 160 of aneyeglass frame 162 (which also functions as mounting 30, as depicted inFIG. 2). Specialized bow 160 may include a rear extension 161 shaped toextend backwards or downwards of the ear 164 and fit closely about aportion of the occipital region of the head.

Wearable positioning devices of various types may be devised, and theinvention is not limited to any particular type of wearable positioningdevice. Wearable positioning devices may include hats, headbands, andhelmets, or other head coverings, apparel or adornments, as are known ormay be devised by those of skill in the relevant art. Exemplary versionsof such devices are described in U.S. Pat. Nos. 4,709,702, 5,323,777,and 6,397,099, incorporated herein by reference in their entirety.Depending on the type of sensors used, the wearable positioning devicemay be close-fitting or relatively loose; for example, some types of EEGelectrodes may need to be pressed tightly against the scalp of asubject, while magnetic or optical signals may be detected without closephysical contact between the sensor and the skin being required. Variousmethods may be devised for positioning sensors with respect to the headof a subject, and the invention is not limited to any particular sensorposition or type of sensor.

In a further alternative embodiment, illustrated in FIG. 8, theadjustable lens system is constructed in form of a contact lens 200 thatis worn on the cornea 202 of eye 10. Other components of the system maybe mounted on or manufactured integrally with contact lens 200, or theymay be packaged separately at a remote location and power and datasignals transmitted to the contact lens 200 inductively or via othersuitable mechanisms. The term ‘remote location’, as used herein, refersto any location not in direct physical contact with contact lens 200,including positions relatively close to the contact lens on the body ofthe subject, more distant locations on the body of the subject, orlocations separated from and at a distance from the body of the subject.

Some embodiments of the systems and devices described herein may also beconfigured as an intraocular lens device 206, as depicted in FIG. 9. Inembodiments in which the system or device is implemented as anintraocular lens system, it is anticipated that typically the naturallens will have been removed and an adjustable intraocular lens device206 implanted within the eye (e.g., within lens capsule 204) asillustrated in FIG. 9. Various adjustable intraocular lens designs maybe used in this embodiment, as exemplified by U.S. Pat. Nos. 4,373,218,4,564,267, 4,601,545, 4,787,903, and 5,108,429, all of which areincorporated herein by reference in their entirety. The eye optics willthen include the cornea. However, in some cases the intraocular lens maybe implanted either in front of or behind the natural lens, so that theeye optics may include the natural lens as well as the cornea. Theintraocular version is not restricted to use with any particularcombination of eye optics, though the correction provided by the lensoptics will typically take into account the degree of focus provided bythe eye optics.

In the exemplary embodiment of FIG. 9, neuromuscular activity isdetected from a sensor 203 in ciliary muscle 22, which neuromuscularactivity may correlate with effort to adjust the focus of the eye.Intraocular lens device 206 may include processor 34, which may be amicrodevice attached to or formed integrally or otherwise associatedwith adjustable lens system 209. Processor 34 and sensor 203 includetransceivers 205 and 207, respectively, to permit the transmission ofdata and power signals between the two devices. A neuromuscular signaldetected by sensor 203 may thus be transmitted to a signal analyzer 56in processor 34. As in other, previously described embodiments, lenssystem controller 58 generates a lens control signal to drive actuationof adjustable lens system 209. Adjustable lens system 209 and processor34 and controller 58 may be powered by power supply 36. Sensor 203 maybe powered remotely by power supply 36, or, alternatively, may include aseparate power supply. In additional variants of this embodiment, one ormore sensors may be positioned in, on or proximate to intraocular lensdevice 206 for detecting neuromuscular signals from ciliary muscles orretina. In still other variants, sensors for detecting neural orneuromuscular signals may be placed in other locations in or on the bodyof the subject, the locations being selected appropriately for detectingspecific neural or neuromuscular signals, and detected signalstransmitted to processor 34. Processor 34 need not be located atintraocular lens device 206. Instead, processor 34 may be located at thesensor, or at some other location, and signals transmitted wirelesslybetween the sensor, processor, and adjustable lens. Operation ofembodiments configured as an intraocular device, as illustrated in FIG.9, is substantially the same as that of other, previously describedembodiments, for example, as illustrated in the flow diagram of FIG. 4or 6.

As illustrated in FIG. 3, the main functional components of processor 34are signal analyzer 56 and lens system controller 58. Processor 34 mayinclude various combinations of analog or digital logic circuitry in theform of discrete components or integrated circuits, hardware, software,and/or firmware under computer or microprocessor control. Processor 34may also include various functional and/or structural components such asmemory, timing, and data processing, transmission and receptionstructures and devices necessary to support the operation of signalanalyzer 56 and lens system controller 58. It will be recognized by oneskilled in the art that the functions and operation of Processor 34 maybe implemented in software, in firmware, in special purpose digitallogic, or any combination thereof, and that the design of processor 34to perform the image analysis and lens system control tasks describedbelow may be performed in various ways by a practitioner of ordinaryskill in the relevant art. Digital signal processing (DSP) chips ordevices suitable for signal processing are commercially available or maybe designed for specific applications. Processor 34 may be implementedin specialized hardware (e.g. as an Application Specific IntegratedCircuit or ASIC) to minimize size and weight of the system whilemaximizing speed of operation. Alternatively, some portions of processor34 may be implemented in software running on a microprocessor-basedsystem. This will provide greater flexibility, relative to specializedhardware, but system size and weight generally will be increased.Although processor 34 (including signal analyzer 56 and lens systemcontroller 58) may be packaged as a single unit, in some cases it may bepreferable to package certain components separately. For example, asdiscussed previously, processor 34 may include a receiver for receivingan image-characterization signal transmitted from a detector and atransmitter for transmitting control signals to the adjustable lenssystem.

In some embodiments, the processor may include a signal input adapted toreceive a time-varying visual focal condition signal detected from thebody of the subject, a pre-processor configured to pre-process thevisual focal condition signal to generate a pre-processed signal, and asignal analyzer configured to determine at least one visual imagequality parameter from the pre-processed signal, which will be sent to alens system controller which generates as output a lens system controlsignal for driving the adjustable lens system. The pre-processor mayperform various functions, including filtering, amplification, artifactremoval, clutter removal, and noise reduction, as are known in the artof signal processing.

Signal analyzer 56 may include appropriately configured digitalcircuitry, hardware, and/or a microprocessor running suitable software.Tasks performed by the neural signal analyzer may include a variety ofmanipulations of one or more neural signals, including pre-processingsteps such as detection of the relevant portions of the detected neuralsignal, processing to increase the signal-to-noise ratio, and analysisof the neural signal to determine values of selected image qualitymetrics. While the full range of neural signal processing tasks may beperformed by the neural signal analyzer in some embodiments, in otherembodiments, selected pre-processing steps may be performed byappropriately configured neural signal detector(s). Appropriateselection of sensor configuration may be used to improve signal quality.For example, by using multiple sensors it may be possible to performsignal averaging, to subtract out common noise components from signal,or to perform multivariate analysis of signals. Such approaches areknown to those skilled in the art of acquisition and processing ofbiological signals. The type of signal processing approach selected maydepend on the specific signals detected. Signal processing methods foruse with electrical and magnetic neural signals have been described, asexemplified by U.S. Pat. Nos. 4,844,086, 4,974,602 5,020,538, 5,655,534,6,014,582, 6,256,531, 6,370,414, 6,544,170, and 6,697,660, all of whichare incorporated herein by reference in their entirety.

Preliminary signal processing to improve the signal to noise ratio orotherwise make the detected signal easier or more convenient to workwith may include a variety of conventional signal processing techniques,such as filtering, signal averaging, adjusting offset and scaling,removal of clutter and artifacts, such techniques being known to thosewith skill in the art.

After preliminary signal processing steps have been completed, theprocessed signal is analyzed to obtain one or more measures of visualfocal condition. The term “visual focal condition” as used herein, meansany of various parameters, also referred to as “quality parameters” or“indicators of focal condition”, which may be determined or derived froma detected neural or neuromuscular signal and used to characterize thevisual input at the retina of the subject, particularly with regard tomeaningful or useful content. The term “quality” is not intended toimply “good quality” or “high quality” but rather quality in general,whether good, bad or mediocre. “Quality parameters”, “indicators offocal condition”, or “focal conditions”, may be determined fromcomponents of a neural or neuromuscular signal that correlate with thequality of the visual input. Components or groups of components of aneural or neuromuscular signal that correlate with a focal condition orquality of a visual input may be referred to as “visual focus-relatedevents”, and may include, for example, a peak or series of peaks ofneural or muscular activity (or indirect indicators of activity such asmetabolism or blood flow) in a signal recorded from a neural orneuromuscular structure.

Image sharpness, or fineness-of-focus (i.e. sharpness or ‘crispness’ offocus of the retinal image, indexed by a relative large fraction of highspatial wavenumber image-pattern on the retinal foveal region) is animportant measure of image quality. Sharpness or fineness-of-focus (orlack thereof) in the retinal image will be reflected in the activationof photoreceptors in the retina and in the neural signals transmittedthrough various portions of the visual pathways. Image focus may bebroken down into a number of components thereof, such as spherical focusor cylindrical focus (with an associated axis of orientation). Choice ofquality metric in certain embodiments may be matched to the attribute(s)of optical aberrations that can be corrected by the adjustable lenssystem or optical system. In some cases, detecting (and subsequentlycorrecting) only one focal attribute may be performed. In other cases,multiple focal attributes may be detected and subsequently corrected.

Image sharpness or fineness-of-focus is not the only measure of imagequality. Depending on the intended application of the system, otherimage attributes or quality metrics may be considered of greaterinterest or importance. These may include metrics such as for, example,image contrast or intensity or spectral content.

The neural or neuromuscular signal is analyzed to determine an indicatorof the focal condition of the imaged visual input. Various components ofthe detected neural or neuromuscular activity may correlate with thequality or state of focus of the image of a visual input. A neuralresponse may be produced in response to a visual input, the focalcondition of the imaged visual input, or an in-focus or out-of-focusstate of the imaged visual input. A component of a neural orneuromuscular signal that correlates with the quality or focal conditionof an imaged visual input may be referred to as a visual focus-relatedevent. Quality or focal condition may refer to one or multipleparameters of focus, e.g., spherical focus, cylindrical focus,cylindrical axis, intensity or sharpness of the image, etc. The neuralresponse may be conscious or unconscious, i.e., the subject may or maynot be consciously aware of the neural response. Providing that theresponse may be measured, it is not necessary that the subject beconsciously aware of it. It is contemplated that components of neuralactivity will correlate with the focal state of the visual input invarious ways. For example, some components of neural activity maycorrelate with the detection of an in-focus imaged visual input. Othercomponents of neural activity may correlate with the detection of anout-of-focus imaged visual input. Still other components of neuralactivity may correlate with the intention of the subject to focus his orher eyes on the visual input. Alternatively, components of neuralactivity may correlate with effort on the part of the subject to focushis or her eyes on the visual input or move his or her eyes (andspecifically, the optic axis of the eyes) toward a particular visualtarget. The non-real-time analysis of EEG signals for identifyingvarious parameters of visual focus, under controlled visual inputconditions, has been demonstrated (see U.S. Pat. No. 5,052,401,incorporated herein by reference).

In some embodiments, the quality parameter may include a time oramplitude measure of a neural signal component that correlates with theperception by the subject of an in-focus state of the imaged visualinput. In other embodiments, the quality parameter may include a time oramplitude measure of a neural signal component that correlates with theperception by the subject of an out-of-focus state of said imaged visualinput. In some out-of-focus states, the neural signal component maycorrelate with the perception by the subject of an imaged visual inputfocused in front of the retina of the eye, while in others it maycorrelate with the perception of a visual input focused behind theretina of the eye. The quality parameter may include a time or amplitudemeasure of a neural signal component that correlates with an effort bythe subject to focus at least one eye on at least portion of the visualinput or alternatively, with effort by the subject to direct the opticalaxis of at least one eye toward at least a portion of the targetedvisual input. Various time and amplitude measures of a peak of adetected neural signal may be used as one or more quality parameters. Inother aspects, the neural signal may be converted to the frequencydomain and the amplitude of one or more frequency components may be usedas quality parameters.

An amplitude measure of a neural signal component may be the amplitudeof a maximum or minimum measured with respect to a selected baselinelevel, or an amplitude difference measure (i.e., the distance betweenselected maxima or minima). A time measure may be a latency or durationof a maximum or a minimum, the width of a peak, or any other temporalfeature of a portion or component of the neural signal. The time measuremay be the time between occurrences of any selected features or eventsin the neural or neuromuscular signal, or duration of a specifiedsequence of features or events.

Neural or muscular activity may correlate with the subject's efforts(either conscious or unconscious) to correct the focus of the visualinput, for example, by adjusting the lens of the eye (by contraction orrelaxation of the ciliary muscle), by adjusting the pupil (bycontraction or relaxation of the iris), or by adjusting facial muscles(squinting) to modify the focal length of the eye. Neural or muscularactivity that correlates with actual, attempted, or planned eyemovements directed toward bringing an imaged visual target into positionon the fovea by moving the optic axis of at least one eye toward achosen visual target, including tracking and vergence movements (i.e.,convergence or divergence), may provide information useful forcontrolling the focal condition of the imaged visual input, as well.Neural activity may be generated in the central nervous system thatcorrelates with muscle activation but occurs prior to actual muscleactivation.

In some embodiments, particular patterns of neuromuscular activity areassociated with particular focal states of the imaged visual input, sothat detected neuromuscular activity serves as a source of feedbackcontrol for adjusting a lens system. For a given subject, it is expectedthat certain patterns of neuromuscular activity will correlate withcertain visual focal conditions in a consistent and predictable manner,at least over the short term. However, for a given subject, thecorrelation may drift over time in some cases. This may be due tovarious causes, ranging from changes in the recording setup (e.g., shiftin position of sensors) to adaptation of the subject to the modifiedvisual input. It is expected that neuromuscular activity that correlateswith a particular focus state will be similar from subject to subject;nevertheless, it may be the case that there will be enoughsubject-to-subject variability that the system may need to be calibratedfor each subject. Therefore, calibration may be performed prior toroutine use of the device according to various embodiments disclosedherein. Furthermore, it may be necessary to calibrate the system fromtime to time during use, to compensate for drift, as discussed above, orfor temporal changes in the subject's visual system. Calibrationsessions may be held at regular intervals or only when needed, asindicated by decreasing system performance. Some embodiments may beconfigured to perform calibration on an on-going basis.

System calibration may be carried out through the use of a trainingprotocol during which the subject is presented with well-defined visualinputs and the neural or neuromuscular activity patterns associated withvarious states of focus of the imaged visual input are determined. Sucha training protocol may be patterned after the methods described in U.S.Pat. Nos. 4,953,968, 4,697,598, and 5,052,401, incorporated herein byreference in their entirety. In general, a series of visual inputs maybe presented in which the focus of an imaged visual input is varied andthe neural or neuromuscular activity produced in response to the visualinputs is measured.

In some embodiments, a predetermined relationship between quality ofvisual input and neural signal may be established by a training protocolthat includes a steps of delivering a series of well-defined visualinput having different values of the quality to the subject, detecting aseries of neural signals produced in response to the series ofwell-defined visual inputs, and determining the quality parameter of theseries of neural signals. In some embodiments, the training protocol maybe performed prior to the use of the system. In other embodiments, thetraining protocol may be performed at intervals during the use of thesystem. The predetermined relationship may be stored in the form ofseries of data representing corresponding values of visual input andfocal condition or quality parameters, or the predetermined relationshipmay be modeled as a mathematical equation or function so that the visualinput may be calculated as a function of one or more focal condition orquality parameters determined from the detected neural or neuromuscularsignal(s), and vice versa.

The system may include a lens system controller configured to receiveone or more quality parameters as input and generate a lens systemcontrol signal for providing closed loop control of the adjustable lenssystem, as a function of the quality parameter(s). The lens systemcontroller may be configured to generate a lens system control signalbased upon a predetermined relationship between the value of at leastone quality parameter and a modified visual input, as discussed above.The predetermined relationship may be defined by stored qualityparameter values and stored corresponding visual input values.Alternatively, the predetermined relationship may be defined by amathematical model that defines at least one quality parameter as afunction of visual input. The lens system controller may be configuredto generate a lens system control signal for updating the setting of theadjustable lens system at a specified update great. The lens systemcontroller may include a device that includes a microprocessor, in whichcase the update rate may be controlled by a timer circuit or by asoftware loop, or by other methods known to those of skill in therelevant art. In still other embodiments, the update rate may be underhardware or firmware control. The lens system controller may be a closedloop controller that is adapted to control the adjustable lens system insubstantially real-time.

FIG. 10 breaks down into greater detail the lens system control processas it may be performed by lens system controller 58 (in other words, theprocess performed at step 86 in FIG.4 and step 154 in FIG. 6). At step166, processor 34 receives focal condition signal 60. At step 168,processor 34 receives lens state signal 68. At step 170, processor 34receives magnification factor input 140, which may be a stored value.Steps 166, 168, and 170 may be performed in any desired order; moreover,in some applications certain of the received parameters may not beadjusted, so the parameter value may be a stored constant value, or aparticular step (e.g., the step of receiving a magnification factorvalue) may be omitted entirely. Subsequently, processor 34 (specificallylens system controller 58) determines a spherical lens strengthadjustment at step 172, determines a cylindrical lens strengthadjustment at step 174, determines a cylindrical axis orientationadjustment at step 176, and determines a magnification adjustment atstep 178. Steps 172, 174, and 176 may be performed in other orders thandepicted in FIG. 10; if one or more of the parameters are not adjusted,one or more of steps 172, 174, and 176 may be omitted as appropriate.Other steps not explicitly noted here but discussed above also may beincluded, e.g., determination of adjustments of lens system spectraltransmissivity, so as to affect the overall brightness and/or relativespectral content of the light processed through the thereby-adjustedlens system. At step 180, lens system controller 58 generates a lenssystem control signal based upon the adjustments determined in steps172, 174, and 176. Depending on the nature of the adjustable lens systemand lens actuator, the control signal may reflect newly determinedabsolute settings for the adjustable lens system, or the control signalmay reflect changes to lens system settings relative to the current lenssystem settings. Adjustable lens system settings may be adjusted tomodify various indicators of focal condition in the neural orneuromuscular signal. Modification of the adjustable lens systemsettings may be selected to move one or more indicators of focalcondition toward a specific target value, in a desired direction, orsimply to produce a change in the image metric or quality attributewhich may be used as a reference value in an adaptive control algorithm.

Determination of lens system adjustment may be performed by the usingwell-known principles of control system design. For example, anexemplary method for adjusting a lens system in response to the focalcondition of visual input may include determining an adjustmentdirection in response to the indicator of focal condition and thenadjusting the lens system in the determined adjustment direction.Determining the adjustment direction may include determining a change inthe value of the indicator of focal condition caused by adjusting thelens system in the determined adjustment direction, by determining thevalue of the indicator of focal condition in the neural responseproduced by a previous instance of the visual input, and determiningfurther change to the lens system adjustment based on the result of theprevious adjustment. For example, if the previous adjustment produced aneural response correlating to a reduction in focal quality of theimaged visual input, the direction of lens system adjustment may bereversed. Conversely, if the adjustment produced a neural responsecorrelating with increased focal quality of the imaged visual input, thenext adjustment step may be in the same direction. Various lens systemparameters (spherical focus, cylindrical focus, etc.) may be adjustedindependently, and the determination of adjustment of each lens systemparameter may be responsive to different indicators of focal condition.In some embodiments, a component of a neural signal indicating qualityof a selected retinal region of the imaged visual field (e.g., thefoveal region) may be measured and a lens system adjustment selected tooptimize the foveal image applied to the entire lens, thus modifying thefocal quality of the image over the entire retina. In other embodiments,the focus may be adjusted separately for areas of the adjustable lenssystem projecting onto different regions of the retina. These and otherapproaches for controlling lens system adjustments may be performed byan appropriately configured or programmed lens system controller, andmay involve the controlled use of a lens system having other than purelyspherical or cylindrical focusing capabilities.

In some embodiments, the controller may be configured to control animage modulator (which may be an adjustable lens system or other opticalelement or optical system) to cause a specified change in an indicatorof focal condition. The controller may be configured to perform acomparison of the indicator of focal condition with a reference focalcondition value and then to control the image modulator to decrease thedifference between the indicator of focal condition and a referencefocal condition value. In some cases it may be desired to increase thedifference between the indicator of focal condition and a referencefocal condition value. Parameters modified by the image modulator mayinclude (but are not limited to) the focal length of the input image,the magnification of the input image, the cylindrical correction of theinput image, or the radiant intensity of the input image.

The lens system controller may control a variety of lens system oroptical system parameters, including any or all of transmissivity of thelens system over one or more spectral wavebands, intensity of lightgenerated by an optical system, effective aperture of one or morecomponents of the adjustable lens system or optical system, transverseposition of at least one optical element relative to the optical axis ofthe eye, or one or more chromatic aberration correcting features of theadjustable lens system.

Timing is an important consideration in the operation of the presentinvention. In order to provide ongoing adaptive visual modification,correction or enhancement, the system updates the setting of theadjustable lens system in real-time or near-real-time. Moreover, inorder to provide true adaptive vision correction, the focus of theadjustable lens system is adjusted to compensate for the current stateof the eye optics and for the current visual input, without a prioriknowledge of the visual input. In some cases this may be accomplished bycompleting a full update cycle (such as the process control loopsdepicted in FIGS. 4 and 6) in an amount of time less than or equal tothe intrinsic accommodation time-response of lens of eye. The intrinsicaccommodation time of the lens of the eye (i.e., that amount of timethat it takes for the lens to adjust to a change in the distance to avisual target) is from about 2 to about 3 seconds for a large change infocal distance, and varies from subject to subject. Accommodation ratesand accommodation distance-ranges vary as functions of age and health,being higher for children and lower for older adults. By adjusting thelens system faster than the intrinsic accommodation time, thelens-actuating musculature of the eye will be minimally worked, thusreducing eye strain and/or fatigue of eye muscles.

In some use-cases, it may be desirable to update the setting of theadjustable lens system at a rate that is as fast, or faster, than thevisual pigment reversal rate of photoreceptors of eye. In particular, insome applications it may be desirable to update the lens setting at arate faster than the visual pigment reversal rate of the photoreceptorshaving the fastest visual pigment reversal rate in the eye. In someembodiments, a controller is configured to provide closed loop controlof the adjustable lens system on an ongoing basis. In some embodiments,the lens system controller is configured to adjust the adjustable lenssystem at a rate faster than the intrinsic accommodation time of thelens of the eye. In other embodiments, the lens system controller isconfigured to adjust the adjustable lens system at a rate faster thanthe visual pigment reversal rate of the photoreceptors of the eye.

It is thought that lens system adjustment update rates of at least aboutonce every three seconds (⅓ Hz) may improve usefulness in generalapplications, and that update rates of about 1 Hz will be preferable forgeneral applications. In higher-performance applications, update ratesof about 3 Hz may be desirable, e.g. to minimize work that must beperformed by the ciliary musculature of the eye's own lens. Update rateshigher than 10 Hz may not provide additional benefit in someapplications, due to the speed limitations inherent in other parts ofthe human visual system, though in some applications, this may not bethe case. Thus, it is thought that update rates in the range of about ⅓to about 10 Hz will be useful in practice, and that update rates in therange of about 1 to about 10 Hz will be more preferred, and that ratesin the range of about 1 to about 3 Hz will be most preferred.

Timing of the update rate for lens system adjustment may be controlledin a number of ways. For example, each update cycle may be initializedby a signal from a timer chip or system clock; a software loop with anapproximately-fixed cycle time may also control the timing. The designof systems using these and other timing control methods are well-knownto those of skill in the art.

In some cases, in order to provide for rapid adjustment between one lenssystem setting and at least one other, rather than utilizing a singleadjustable lens system and modifying the setting of that lens system,two or more adjustable lens systems or optical subsystems may be used,and suitable optics used to switch between the two or more lens systems.In the exemplary case of two lens systems, one useful application ofthis embodiment is to adjust the first and second optical subsystems toprovide correction for near and far vision, respectively. Thus,switching between the two optical subsystems, the subject would obtaincorrection similar to what is currently provided by bi-focal lenses, butin an automated and potentially high-speed fashion.

This approach is depicted schematically in FIG. 11. First opticalsubsystem 183 and second optical subsystem 184 have optical properties(e.g. spherical focal length, cylindrical focal power, and axis oforientation) that can be adjusted independently. First optical subsystem183 and second optical subsystem 184 are set up in parallel between avisual input 40 and the eye of the subject. Visual input 40 may beswitched rapidly between optical subsystem 183 and optical subsystem 184by switching element 185, which may be an adjustable reflector orrefractive element, such as a lens. Each of optical subsystem 183 andoptical subsystem 184 may be an adjustable lens or lens system,controlled by a lens system controller as described previously. Afterpassing through either optical subsystem 183 or optical subsystem 184,an intermediate incident image 40 a or 40 b, respectively, will bedelivered to the eye of the subject. The optical system as depicted inFIG. 11 may be used in connection with lens control mechanisms asdescribed previously herein. Another method for providing rapidswitching between optical subsystem having different settings is toprovide two or more optical subsystems having transmissivitiescontrollable between substantially complete transmissivity andsubstantially zero transmissivity, such that the amount of light that istransmitted through each subsystem can be controlled. Parallel segmentsare maintained in the optical path between the eye and the visualtarget; by adjusting first and second-or-more controllabletransmissivities appropriately, it is possible to switch rapidly betweenfirst and second-or-more segments. Parallel optical subsystems of thistype may be constructed in the form of an electroactive lens system inwhich individually controllable lens areas are interleaved, asillustrated in FIG. 12, by microfabrication techniques known to those ofskill in the relevant art. Thus, lens regions 186 correspond to a firstoptical subsystem, while lens regions 187 correspond to a second opticalsubsystem; adjustment of the transmissivities of lens regions 186 toprovide full transmissivity while adjusting the transmissivities of lensregions 187 to substantially-zero transmissivity thus routes the visualinput through the first optical subsystem. Conversely, adjustment of thetransmissivities of lens regions 186 to provide substantially zerotransmissivity while adjusting the transmissivities of lens regions 187to full transmissivity routes the visual input through the secondoptical subsystem. Different interleaving patterns can support three ormore different optical subsystems.

Switching between two or more optical subsystems according to either ofthe above described methods could be controlled manually by the subject,by pushing a button or intentionally generating a readily detectedcontrol signal (a blink, etc.) or controlled automatically in responseto vergence movement of eyes, change in distance to the visual target(detected, for example, by a rangefinder), or a sufficiently largechange in focal quality of the detected image. According to either ofthe above embodiments, one or more of the optical subsystems may beadjusted to the current state of the visual input and the eye optics ofthe subject in order to compensate for gradual changes in imaged focalquality, while switching between the subsystems may be used tocompensate for more abrupt changes (for example, when the subjectswitches abruptly from a near vision task, such as reading the dashboarddisplay of a car, to a distance vision task, such as looking at the roadahead).

Various components of the system, including the adjustable lens system,processor, and input and output image detectors may require some form ofpower supply. While the invention is not limited to any particular typeof power supply, if the power supply is to be included in an eyeglassframe, contact lens, or intraocular lens, it will typically be small andlightweight. For embodiments in which the adjustable lens system ismounted in an eyeglass frame, the device may be conveniently powered bya battery. Photovoltaic cells may also be used to provide power to thedevice. The power supply and possibly other components of the device aswell may be located at a distance from the adjustable lens system, andpower transmitted to the device, e.g. by inductive coupling or bypower-beaming. The power supply may include an inductive coil or anantenna.

In some embodiments, the body of the subject may be used as a powersource for powering the device. Various “energy scavenging” or “energyharvesting” devices are known, or may be developed (see e.g., U.S. Pat.Nos. 6,615,074, 6,655,035 and 6,768,246, and published U.S. Patentapplications 20030014091 and 20030165648, all of which are incorporatedherein by reference). For example, devices that capture energy from bodymovement of the subject (e.g., inertial devices as are used to powerself-winding wristwatches) may be used to power the device. Pressure andchemical gradients within the body may also provide energy for poweringoperation of the device. For example, energy may be captured from thesystolic-diastolic cycle or pulsatile blood flow of the subject, orthrough a micro-turbine or powered shunt placed in the respired airflowof the subject. Although reference has been made to a single powersupply, the invention is not limited to use of a single power supply,and the invention includes embodiments in which separate power suppliesmay be used for different parts of the system or during differentcircumstances of operation of the system, or both. Various components ofthe system may have different power sources in the system as a whole,may have one or multiple power sources of various types and is notlimited to any specific power source configuration.

As depicted in FIG. 2, adjustable lens system 26 may be positioned withrespect to eye 10 of the subject 28 via mounting 30. Mounting 30 maytake various forms, examples of which are illustrated in FIGS. 13 and14. Mounting 30 may be an eyeglass frame, as depicted previously in FIG.2, or helmet mounted frame 190, as in FIG. 13. Helmet 192 may be of thetype worn by an airplane pilot, for example. Alternatively, mounting 30may include a mechanical linkage 194 secured to a wall or ceiling ormounted on a base set on a table or floor, such that, in use, thesubject stands or sits, and the equipment is held in fixed relationshipto the subject's eye, but is not attached directly to the subject'shead. In general, as used herein, the term ‘base’ refers to any supportor positioning structure to which mounting 30 is connected by a linkagein order to maintain the lens or optical system in proper relation tothe subject's eye. As with the embodiments of the system in whichmounting 30 is an eyeglass frame, other components of the system may bemounted on the mounting, or may be packaged separately.

The adjustable lens system may be implemented in the form of an eyeglasslens, a contact lens, or intraocular lens. The adjustable lens system(or at least a portion thereof) may be formed in, on, or in spatialassociation with such lenses, including placement behind or in front ofsuch lenses, in addition to being housed in or formed integrally withsuch lenses. It may also be implemented in other forms; as depicted inFIGS. 13 and 14 it may be mounted in a helmet or in a stationary mountof the type used for optometric devices. The latter implementations arebulkier and present greater flexibility with regard to choice of systemcomponents and integration thereof. Although a helmet is depicted inFIG. 13, it will be appreciated that optical system components may bepositioned with respect to the head by a variety of head mounted devicesor structures, including headbands, hats, and other head coverings,which may not only provide support to system components but alsofunction as head apparel or adornment. For implementation of the systemas eyeglasses, and more particularly in the form of a contact lens orintraocular lens, system components that are to be located in or on thelens (e.g., the lens actuator and possibly sensor for detecting a neuralor neuromuscular signal) will preferably be very small,light weight andof modest time-averaged power demand. Certain components of the systemmay be packaged separately from the adjustable lens system, therebyreducing size and weight constraints. For example, certain components ofthe system can be packaged in a case that can be carried in, forexample, the subject's pocket. Wireless transmission of data, controland power signals may be achieved via RF transmission or inductivecoupling or beaming. Various portions of the system may also includetransmission and receiving devices to provide for sending signalsbetween physically separated system components. Digital signals arethought to be particularly suited for effectively error-freetransmission in such embodiments, but the practice of the methods hereinare not limited to any particular method of data transmission. Foreyeglass, helmet, or stationary mount devices, wiring may besatisfactory for carrying power and data and control signals.

With regard to the hardware and/or software used in neural signaldetection and analysis, as well as various aspects of device control,those having skill in the art will recognize that the state of the arthas progressed to the point where there is little distinction leftbetween hardware and software implementations of aspects of systems; theuse of hardware or software is generally (but not always, in that incertain contexts the choice between hardware and software can becomesignificant) a design choice representing cost vs. efficiency orimplementation convenience tradeoffs. Those having skill in the art willappreciate that there are various vehicles by which processes and/orsystems described herein can be effected (e.g., hardware, software,and/or firmware), and that the preferred vehicle will vary with thecontext in which the processes are deployed. For example, if animplementer determines that speed and accuracy are paramount, theimplementer may opt for a hardware and/or firmware vehicle;alternatively, if flexibility is paramount, the implementer may opt fora solely software implementation; or, yet again alternatively, theimplementer may opt for some combination of hardware, software, and/orfirmware. Hence, there are several possible vehicles by which theprocesses described herein may be effected, none of which is inherentlysuperior to the other in that any vehicle to be utilized is a choicedependent upon the context in which the vehicle will be deployed and thespecific concerns (e.g., speed, flexibility, or predictability) of theimplementer, any of which may vary. Those skilled in the art willrecognize that optical aspects of implementations will requireoptically-oriented hardware, software, and or firmware.

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beimplicitly understood by those with skill in the art that each functionand/or operation within such block diagrams, flowcharts, or examples canbe implemented, individually and/or collectively, by a wide range ofhardware, software, firmware, or virtually any combination thereof. Inone embodiment, several portions of the subject matter subject matterdescribed herein may be implemented via Application Specific IntegratedCircuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signalprocessors (DSPs), or other integrated formats. However, those skilledin the art will recognize that some aspects of the embodiments disclosedherein, in whole or in part, can be equivalently implemented in standardintegrated circuits, as one or more computer programs running on one ormore computers (e.g., as one or more programs running on one or morecomputer systems), as one or more programs running on one or moreprocessors (e.g., as one or more programs running on one or moremicroprocessors), as firmware, or as virtually any combination thereof,and that designing the circuitry and/or writing the code for thesoftware and/or firmware would be well within the capabilities of one ofskill in the art in light of this disclosure. In addition, those skilledin the art will appreciate that the mechanisms of the subject matterdescribed herein are capable of being distributed as a program productin a variety of forms, and that an illustrative embodiment of thesubject matter described herein applies equally regardless of theparticular type of signal bearing media used to actually carry out thedistribution. Examples of a signal bearing media include, but are notlimited to, the following: recordable type media such as floppy disks,hard disk drives, CD ROMs, digital tape, and computer memorysemiconductor devices; and transmission type media such as digital andanalog communication links using TDM or IP-based communication links(e.g., links carrying packetized data).

In a general sense, those skilled in the art will recognize that thevarious aspects described herein which can be implemented, individuallyand/or collectively, by a wide range of hardware, software, firmware, orany combination thereof can be viewed as being composed of various typesof “electrical circuitry.” Consequently, as used herein “electricalcircuitry” includes, but is not limited to, electrical circuitry havingat least one discrete electrical circuit, electrical circuitry having atleast one integrated circuit, electrical circuitry having at least oneapplication specific integrated circuit, electrical circuitry forming ageneral purpose computing device configured by a computer program (e.g.,a general purpose computer configured by a computer program which atleast partially carries out processes and/or devices described herein,or a microprocessor configured by a computer program which at leastpartially carries out processes and/or devices described herein),electrical circuitry forming a memory device (e.g., forms of randomaccess memory), and/or electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment).

Those skilled in the art will recognize that it is common within the artto describe devices for neural and/or neuromuscular signal detection andanalysis, optical system control, and/or processes in the fashion setforth herein, and thereafter use standard engineering practices tointegrate such described devices and/or processes into visionenhancement systems as exemplified herein. That is, at least a portionof the devices and/or processes described herein can be integrated intoa vision enhancement system via a reasonable amount of experimentation.Those having skill in the art will recognize that such systems generallyinclude one or more of a memory element such as volatile and/ornon-volatile semiconductor-based memory, processors such asmicroprocessors and digital signal processors, computational-supportingor -associated entities such as operating systems, user interfaces,drivers, sensors, actuators, applications programs, one or moreinteraction devices, such as data ports, control systems includingfeedback loops and control-implementing actuators (e.g., devices forsensing position and/or velocity and/or acceleration ortime-rate-of-change thereof; control motors for moving and/or adjustingcomponents and/or quantities). A typical vision enhancement system maybe implemented utilizing any suitable available components, such asthose typically found in appropriate computing/communication systems,combined with standard engineering practices.

The foregoing-described aspects depict different components containedwithin, or connected with, different other components. It is to beunderstood that such depicted architectures are merely exemplary, andthat in fact many other architectures can be implemented which achievethe same functionality. In a conceptual sense, any arrangement ofcomponents to achieve the same functionality is effectively “associated”such that the desired functionality is achieved. Hence, any twocomponents herein combined to achieve a particular functionality can beseen as “associated with” each other such that the desired functionalityis achieved, irrespective of architectures or intermediate components.Likewise, any two components so associated can also be viewed as being“operably connected”, or “operably coupled”, to each other to achievethe desired functionality.

While particular aspects of the present subject matter described hereinhave been shown and described, it will be obvious to those skilled inthe art that, based upon the teachings herein, changes and modificationsmay be made without departing from this subject matter described hereinand its broader aspects and, therefore, the appended claims are toencompass within their scope all such changes and modifications as arewithin the true spirit and scope of this subject matter describedherein. Furthermore, it is to be understood that the invention isdefined by the appended claims. It will be understood by those withinthe art that, in general, terms used herein, and especially in theappended claims (e.g., bodies of the appended claims) are generallyintended as “open” terms (e.g., the term “including” should beinterpreted as “including but not limited to,” the term “having” shouldbe interpreted as “having at least,” the term “includes” should beinterpreted as “includes but is not limited to,” etc.). It will befurther understood by those within the art that if a specific number ofan introduced claim recitation is intended, such an intent will beexplicitly recited in the claim, and in the absence of such recitationno such intent is present. For example, as an aid to understanding, thefollowing appended claims may contain usage of the introductory phrases“at least one” and “one or more” to introduce claim recitations.However, the use of such phrases should NOT be construed to imply thatthe introduction of a claim recitation by the indefinite articles “a” or“an” limits any particular claim containing such introduced claimrecitation to inventions containing only one such recitation, even whenthe same claim includes the introductory phrases “one or more” or “atleast one” and indefinite articles such as “a” or “an” (e.g., “a” and/or“an” should typically be interpreted to mean “at least one” and/or “oneor more”); the same holds true for the use of definite articles used tointroduce claim recitations. In addition, even if a specific number ofan introduced claim recitation is explicitly recited, those skilled inthe art will recognize that such recitation should typically beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, typicallymeans at least two recitations, or two or more recitations).Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” is used, in general such a constructionis intended in the sense of one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, and C”would include but not be limited to systems that have A alone, B alone,C alone, A and B together, A and C together, B and C together, and/or A,B, and C together). In those instances where a convention analogous to“at least one of A, B, or C, etc.” is used, in general such aconstruction is intended in the sense of one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, or C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together).

Although the methods, devices, systems and approaches herein have beendescribed with reference to certain preferred embodiments, otherembodiments are possible. As illustrated by the foregoing examples,various choices of adjustable lens system configuration and neural orneuromuscular signal sensor configuration may be within the scope of theinvention. As has been discussed, the choice of system configuration maydepend on the intended application of the system, the environment inwhich the system is used, cost, personal preference or other factors.Image analysis and lens system control processes may be modified to takeinto account choices of lens system and image detector configuration,and such modifications, as known to those of skill in the arts of imageanalysis, control system design, and other relevant arts, may fallwithin the scope of the invention. Therefore, the full spirit or scopeof the invention is defined by the appended claims and is not be limitedto the specific embodiments described herein.

1. A system for modifying the vision of a subject, comprising: a) anadjustable lens system adapted to modify a visual input to provide amodified visual input to the subject; b) at least one sensor fordetecting a neural signal from said subject; c) a signal processorconfigured to receive as input said neural signal and to process saidneural signal to generate as output at least one quality parameterrepresenting a quality of said modified visual input; and d) a lenssystem controller configured to receive said at least one qualityparameter and to generate a lens system control signal for providingclosed loop control of said adjustable lens system as a function of saidat least one quality parameter.
 2. The system of claim 1, wherein saidvisual input is a time-varying visual input.
 3. The system of claim 1,wherein said controller is configured to provide closed loop control ofsaid adjustable lens system on an ongoing basis.
 4. The system of claim1, wherein said at least one sensor is adapted to detect anelectromagnetic signal.
 5. The system of claim 4, wherein said at leastone sensor is adapted to detect an electroencephalographic signal. 6.The system of claim 4, wherein said at least one sensor is adapted todetect a magnetoencephalographic signal.
 7. The system of claim 1,wherein said neural signal is an optoelectronic measure of neuralactivity.
 8. The system of claim 7, wherein said neural signal isdetected using near Infra-Red imaging.
 9. The system of claim 7, whereinsaid neural signal is an optoelectronic measure of at least oneindicator of brain metabolic activity.
 10. The system of claim 7,wherein said neural signal is an optoelectronic measure of at least oneaspect of blood flow in the brain.
 11. The system of claim 1, whereinsaid at least one sensor comprises at least one electrode.
 12. Thesystem of claim 11, wherein said at least one sensor comprises an arrayof electrodes located at a plurality of positions on the head of saidsubject.
 13. The system of claim 1, wherein said at least one sensorcomprises at least one electrode implanted within the body of saidsubject.
 14. The system of claim 1, wherein said at least one sensorcomprises at least one optoelectronic sensor.
 15. The system of claim 1,further comprising a positioning device adapted for positioning said atleast one sensor with respect to the head of said subject.
 16. Thesystem of claim 15, wherein said positioning device comprises a wearablepositioning device.
 17. The system of claim 16, wherein said positioningdevice includes a headband.
 18. The system of claim 16, wherein saidwearable positioning device is in the form of a hat, head covering, headapparel or head adornment.
 19. The system of claim 16, wherein saidwearable positioning device comprises a helmet.
 20. The system of claim16, wherein said wearable positioning device comprises an eyeglassframe.
 21. The system of claim 20, wherein said eyeglass frame comprisesa specialized bow, said bow including an extension shaped so that duringuse said extension extends backwards or downward of an ear of saidsubject to fit closely about a portion of the head of said subject. 22.The system of claim 1, wherein said adjustable lens system comprises anelectroactive lens system.
 23. The system of claim 1, wherein saidadjustable lens system comprises a fluid lens.
 24. The system of claim23, wherein said fluid lens comprises an elastically deformable shellsurrounding an inter-lens space, and wherein adjusting said fluid lenscomprises adjusting a volume or pressure of fluid in said inter-lensspace.
 25. The system of claim 23, wherein said fluid lens includes anoptically-functional interface between two immiscible fluids.
 26. Thesystem of claim 1, wherein said lens system controller is adapted togenerate said lens system control signal based upon a pre-determinedrelationship between the value of said at least one quality parameterand said modified visual input.
 27. The system of claim 26, wherein saidpre-determined relationship is based upon stored quality parametervalues and stored corresponding visual input values.
 28. The system ofclaim 26, wherein said pre-determined relationship is defined by amathematical functional relationship relating said at least one qualityparameter to said visual input.
 29. The system of claim 1, wherein saidlens system controller is configured to generate a lens system controlsignal for updating the setting of said adjustable lens system at aspecified update rate.
 30. The system of claim 29, wherein said lenssystem controller comprises a device including a microprocessor, andwherein said update rate is controlled by a timer circuit.
 31. Thesystem of claim 29, wherein said lens system controller comprises adevice including a microprocessor, and wherein said update rate iscontrolled by a software loop.
 32. The system of claim 29, wherein saidlens system controller comprises digital hardware, and wherein saidupdate rate is under hardware or firmware control.
 33. The system ofclaim 1, wherein said lens system controller is configured to adjustsaid adjustable lens system at a rate greater than the reciprocal of theintrinsic accommodation time of the lens of said eye.
 34. The system ofclaim 1, wherein said lens system controller is configured to adjustsaid adjustable lens system at a rate greater than the greatest of thevisual pigment reversal-rates of the photoreceptors of said eye.
 35. Thesystem of claim 1, wherein said lens system controller is configured toadjust the distance of said lens system relative to an eye surface ofsaid eye.
 36. The system of claim 1, wherein said lens system controlleris configured to adjust the transverse position of said lens system withrespect to the optical axis of said eye.
 37. The system of claim 1,wherein said lens system comprises an adjustable effective aperture. 38.The system of claim 26, wherein said pre-determined relationship isestablished through a training protocol comprising: a) delivering aseries of well-defined visual inputs having different values of saidquality to said subject; b) detecting a series of neural signalsproduced in response to said series of well-defined visual inputs fromsaid subject; c) determining said quality parameter of said series ofneural signals; and d) determining a relationship between said qualityof said visual inputs and said quality parameter of said neural signals.39. The system of claim 38, wherein said training protocol is performedprior to use of said system.
 40. The system of claim 38, wherein saidtraining protocol is performed at intervals during the use of saidsystem.
 41. The system of claim 1, wherein said adjustable lens systemhas an adjustable focal length.
 42. The system of claim 1, wherein saidadjustable lens system has an adjustable magnification.
 43. The systemof claim 1, wherein said adjustable lens system has an adjustablespherical optical strength.
 44. The system of claim 1, wherein saidadjustable lens system has an adjustable cylindrical optical correction.45. The system of claim 44, wherein said adjustable cylindrical opticalcorrection comprises an adjustable cylindrical optical strength.
 46. Thesystem of claim 44, wherein said adjustable cylindrical correctioncomprises an adjustable cylindrical axis of optical orientation.
 47. Thesystem of claim 42, wherein said lens system controller is adapted toaccept a magnification factor input.
 48. The system of claim 47, whereinsaid lens system controller is adapted to adjust said lens system inresponse to said magnification factor and said quality parameter. 49.The system of claim 1, wherein said adjustable lens system has anadjustable transmissivity in at least one spectral waveband.
 50. Thesystem of claim 1, wherein said lens system controller is configured tocontrol at least one characteristic of said adjustable lens system. 51.The system of claim 1, wherein said lens controller is configured tocontrol multiple characteristics of said adjustable lens system.
 52. Thesystem of claim 1, further comprising a lens system actuator thatactuates said adjustable lens system in response to said lens systemcontrol signal.
 53. The system of claim 1, further comprising a powersource.
 54. The system of claim 53, wherein said power source comprisesat least one of a battery, a photovoltaic cell, and an energy-scavengingdevice.
 55. The system of claim 53, wherein said power source isconnected to at least one other component of said system throughinductive coupling or power beaming.
 56. The method of claim 1, whereinsaid quality parameter includes a time or amplitude measure of a neuralsignal component that correlates with the perception by said subject ofan in-focus state of said visual input.
 57. The method of claim 1,wherein said quality parameter includes a time or amplitude measure of aneural signal component that correlates with the perception by saidsubject of an out-of-focus state of said visual input.
 58. The method ofclaim 57, wherein said neural signal component correlates with theperception by said subject of a visual input focused in front of thelight-sensitive surface of the retina of said eye.
 59. The method ofclaim 57, wherein said neural signal component correlates with theperception by said subject of a visual input focused behind thelight-sensitive surface of the retina of said eye.
 60. The method ofclaim 1, wherein said quality parameter includes a time or amplitudemeasure of a neural signal component that correlates with an effort bysaid subject to focus at least one eye on at least a portion of saidvisual input.
 61. The method of claim 1, wherein said quality parameterincludes a time or amplitude measure of a neural signal component thatcorrelates with an effort by said subject to direct the optical axis ofat least one eye toward at least a portion of said visual input.
 62. Thesystem of claim 1, wherein said quality parameter comprises theamplitude of a peak of said detected neural signal.
 63. The system ofclaim 1, wherein said quality parameter comprises a time or amplitudemeasure of a time-series of peaks of said detected neural signal. 64.The system of claim 1, wherein said quality parameter comprises anamplitude of at least one frequency component of said detected neuralsignal.
 65. A system for modifying the vision of a subject, comprising:a) an adjustable optical system for modifying a real-time varying inputimage impinging on an eye of a subject; b) a detector for detecting aneural signal produced by said subject in response to said input image;c) a signal analyzer for performing an analysis of said neural signal todetermine whether said input image is in focus on the light-sensitivesurface of the retina; and d) an optical system controller adapted tocontrol said adjustable optical system responsive to said analysis ofsaid neural signal to bring said input image into focus on thelight-sensitive surface of the retina.
 66. The system of claim 65,wherein said adjustable optical system comprises: a) a first subsystemhaving a first spherical focal length, a first cylindrical focal power,a first axis of cylindrical-focal orientation, and a first controllabletransmissivity; b) a second subsystem having a second spherical focallength, a second cylindrical focal power, a second axis ofcylindrical-focal orientation, and a second transmissivity; and c) aswitch whereby said first transmissivity and said second transmissivitycan be adjusted to selectively direct said input image through one ofsaid first subsystem and said second subsystem.
 67. The system of claim66, wherein said switch is configured to be controlled by said subject.68. The system of claim 66, wherein said switch is configured to becontrolled automatically.
 69. The system of claim 68, wherein saidswitch is configured to be controlled automatically in response tovergence movement of at least one eye of said subject.
 70. The system ofclaim 68, further comprising a range finder for determining the distancefrom said system to a visual target, wherein said switch is configuredto be controlled automatically in response to the determined distance toa said visual target.
 71. The system of claim 66, further comprising amounting adapted for positioning said adjustable optical system withrespect to said eye of said subject.
 72. The system of claim 71, whereinsaid mounting comprises an eyeglass frame.
 73. The system of claim 71wherein said mounting comprises a frame mounted on a helmet, headband,hat, head covering, head apparel or head adornment.
 74. The system ofclaim 71, wherein said mounting comprises a mechanical linkage connectedto a base.